1. Field of the Invention
The present invention generally relates to a video endoscope and, more particularly, toward an endoscope with a rotatable video camera.
2. Description of Related Art
When used in procedures in the human body, endoscopes frequently need to be rotated or swiveled so that an implement fitted into the endoscope may reach a particular place or, for instance, to be able to observe laterally when the objective lens is oblique. When the video camera however is irrotationally mounted in the video endoscope, the monitor picture shall rotate jointly with the video endoscope. This feature is highly taxing for the surgeon.
Accordingly video endoscopes of this kind are fitted with a rotatable camera which can be rotated relative to the video endoscope rotation such that the monitor picture shall remain unaffected by camera rotation.
The German patent document U 20,113,031 discloses a video endoscope wherein, on well known design grounds coming into play in particular with oblique objective lenses, the objective lens is affixed to the tube enclosing the swivel unit, and the tube is fixed in position relative to the endoscope as a whole. Accordingly, in this design the video camera rotates relative to the objective lens. The rotational system of video camera and rotational element is supported on two swivel bearings to assure accurate guidance and bracing of the video camera relative to the objective lens. Moreover, an axially fixed bearing ensures the axial position between camera and objective lens.
This known design incurs the drawback that the axial bearing is situated at the proximal end of the swivel element. If the endoscope is being bent and when there are temperature changes such as frequently occur when using video endoscopes (body temperature/room temperature), the distance between objective lens and video camera may change and degrade the focus, i.e., they may entail a blurred picture.